Scaling Up My Foam Bricks

Following on from my smaller experiments using foam which had worked really well I decided to scale up to reduce the amount of seams throughout the corners, this will also save me time in the long run, rather than making lots and lots of small pieces.

Using some of the panels I had already created for my tunnel I decided on the size of sheet of my new brickwork template 760mm x 500mm. I got this laser cut on a piece of 3mm MDF which was very flexible and is exactly what I needed for my next step.

Instead of using plaster, I decided to use a white clay to be able to release the clay much more easily from the MDF template, It will also stop air bubbles from occurring. I took myself to the ceramics room where there is an industrial roller. I began putting my clay in-between the cloth provided which stops the clay from sticking to the roller as well as the wooden boards on the outside top and bottom. Adding the wood piece on top allowed me to squash the clay bit more. Once I had made the clay into the flat rectangular shape I needed I made sure to get rid of any imperfections caused by the fabric. I did this by really pulling on the fabric and flattening any creases.

I then placed my MDF brick template carefully on top of my clay making sure the clay covers all of the edges. I decided not to put the top piece of wood on because I thought it may press my template in too far into the clay. I placed the top piece of fabric on and then I put it through the roller, once over and then once back to make sure there would be no shifting of the mould. I then

I carefully and slowly peeled the MDF template off, which came of really nicely. I placed the this onto a large piece of plastic to make sure it is transportable. I began building up the edges to seal in the clay to stop any leakage of the silicone.

I brought my clay mould to my workspace to allow me to work on it further. I sprayed the clay with a mould release just in case of any sticking and mixed up 1kg of Silicone which didn't cover the entire mould, which I knew it wouldn't to begin with. I bought a second silicone to allow me to top off the mould which I ended up using another 1kg, making the mould a total of 2kg of silicone used. The two silicones even though they are the same brand and the same mixture, managed to become different tones of peach? Im not sure as to why this has happened however it cured absolutely fine and Is very durable.

I left the silicone to cure for 24 hrs and carefully pulled the silicone away from the clay. There must of been some air bubbles trapped in-between the narrow gaps in-between the bricks as there is a lot of parts of the silicone missing where the should be... however this shouldn't effect the overall appearance of the bricks in the foam.

I gave the silicone mould a really good clean as there as pieces of clay stuck in the corners and edges. I then covered the plastic sheet I used to transport the clay mould with two black sacks to make sure nothing sticks to it.

I then trimmed off the excess edges of my silicone allow a frame to fit perfectly around it. I made a 4 part frame out of a 8mm plywood (2 x 760mm & 2 x 500mm). I used Gorilla wood glue to stick this together and allowed this to dry, once dry I used a nail gun to place two nails in each connection to make it stronger. I measured the top space of the silicone mould and made a top piece to sit on top to allow the silicone to always be the same thickness, I covered this piece of wood also in a black bag. I sprayed a mould release onto the silicone and the plastic backs surrounding it to stop the foam from sticking. I bought some Mouldlife Pro-Cell S4 expanding foam from the Hatch. Which I soon learnt was way out of its use by date. With a 6 months shelf life from new...the Pro-Cell I had been given was years out of date due to the lack of use. The foam is supposed to expand up to 8 times the amount you originally put in, however I was only able to get the foam to almost twice its size... This has set me back a little bit. However the Hatch is bringing in a new batch next week which they are allowing me to have a replacement for the one I already bought.